In pairing displays of work by photographers Helen Levitt and Leo Rubinfien, Stanford's Cantor Arts Center has done more than create a compare-and-contrast anthology. It provokes visitors to ask whether people in cities unconsciously evolve a lingua franca of gesture or demeanor that transcends communities and that the camera can see, and perhaps also shape.

Levitt (1913-2009), a New Yorker who seldom left her native city, would probably have affirmed it. Rubinfien, born 40 years later in Chicago, has traveled extensively, detecting evidence of urbanization's homogenizing - or perhaps harmonizing - influence on populations.

Levitt saw a single city as the world. Rubinfien sees the world turning into a single city. Their divergent visions capture evolving changes in people's sense of mobility, in their coding of personal and cultural identity.

The photographers' respective bodies of work overlap in time, but they register ongoing changing attitudes toward the camera. Levitt sometimes used a right-angled viewfinder, following Walker Evans' example, to capture people unawares. Rubinfien more often meets his subjects through the lens and apparently finds them quite prepared to be in pictures.

He hints, as do the shows taken together, that the camera's near-ubiquity has globalized peoples' expectations of what might follow from being photographed - notoriety, envy, admiration, a jolt for a cause.

Stanford's theater department has helped give Levitt's work a prop-heavy installation that works only to the extent that it makes the pictures' grouping by themes harder to overlook. An antique-looking park bench provides seating to watch Levitt's engrossing and rarely presented short film "In the Street" (1941-52).

Two for two: Creative collaboration has mushroomed in contemporary art, but I cannot recall anyone delving into its most obvious implicit themes - friendship and cooperation - as Hannah Ireland and Annie Vought do in their joint show at Unspeakable Projects.

Ireland has carved up floor and wall space with salvaged picket fence, baring the teeth of this symbol of idyllic neighborliness.

Vought shows several of her dazzlingly ornate paper cuts of handwritten letters, including one that Ireland sent her during their teens.

In more recent pieces, Vought traces every whorl of frenzied scratching-out in letters probably never sent, making literalness and illegibility converge in nearly complete abstraction.

But the videos offer the most memorable surprises to visitors not already familiar with Vought's astonishing paper cuts.

For the silent "Can Pick You Up or Meet You There, Either Way" (2011), the collaborators drove two posts into the beach, upright and parallel, about 5 feet apart and 3 feet tall, each just wide enough to stand atop on only one leg.

Against a blank sky, before a fixed camera, Ireland and Vought enter the frame and each tries to surmount a post without a ladder or other prop.

Vought finally helps Ireland onto a perch, where she teeters effortfully until Vought manages solo to stand on hers. They join hands, beginning a footworkless dance of reciprocal rebalancing.

"Can Pick You Up ..." joins a line of task-oriented performances that connects Marina Abramoviæ, Vito Acconci, Richard Serra and others. The piece also revises the "living sculpture" performances that won early art world fame for Gilbert and George.

But "Can Pick You Up ..." and two other videos here have an affectionate, mildly comic spirit too seldom seen in performance art.

In one piece, Ireland and Vought contrive to open and share a bottle of champagne with their hands joined by Chinese finger traps.

In the other, they work their way from a couch to the floor to standing and hopping out of the frame, each bound neck to ankles in cellophane, like a kidnap victim.

The American backbeat of pathological individualism lends these collaborations a poignancy, power and political edge that we might otherwise miss.

In a New York Minute: Photographs by Helen Levitt; Paths Through the Global City: Photographs by Leo Rubinfien: Through May 1. Cantor Arts Center, Stanford University, Stanford. (650) 723-4177. www.museum.stanford.edu.